Telephone system



Oct. 27, 1931. M. B. sTAzAK TELEPHONE SYSTEM Filed Oct. 29. 1929 5 Sheets-Sheet 1 OC. 27, 1931. M B. STAZAK 1,829,070

Y TELEPHONE SYSTEM Filed ooi. 29,1929 3 sheets-sheet 2 jtwzr.-

Oct. 27, 1931. M. B. sTAzAK 1,829,070

TELEPHONE SYSTEM Filed Oct. 29, i929 3 Sheets-Sheet 5 Patented Oct. 27,` 1931 unire-nx*srAfrEsf MICHAEL' BK STAZAK', VOF? CHIGAGOL ILLINOIS A'SSIGNQR T0 KELLOGG SWITGHBOARD". AND "SUPPLY COMPANY; OF'v CHIGAGQILLINOISf AL COR'PQRLATIONILLINOIS TELEPHONE {SYSTEM- My .invention :relatesto telephone systems andY -more yp:artic'ularly ,to systems in whichV a number i of sub'scribers lines yterminate :at a private automatic exchange which 1s operativelyronnected to al main exchangeof the line of the calling `subscriber; and connect it to'. aconncctorswitch Which is set in ,Operation by impulsesofcurrent controlledfat 4the call-ing subscribcrs stationv :to select .the line.

associated .With ,the called 7subscriber or the 1 5 main exchangeor.the-attendant ,at the privateautomatic t exchange.:

A feature of v my invention is the prckivision` offa 'starting' circuit whereby anyone of `the finder switches in' the group` may be-removed .20 from the groupwithout affecting th'e'operaa` tion ot the othernderswitchesin the group.y

Another feature of my.L inventionconsists of.v a; group ylousy, alarm which' informs the calling subscriber i of the, -busy -condition of 25 the; .linden switches `ofthe fgroupwith which@ he isconnected.

A further feature. of my; inventionisrthe provisionvof arplurality of tones supplied tothe calling-subscribes lineto indicatethe condition yof the connecting` apparatus at the private exchange.

A feature ofmy invention isthe provision ofi mean-s whereby the called ,party controls the releaseo-the apparatus on local connectionsand the party originatingfthe. call con.-` trolsethefrelease on. trunk i. connections. p

Another feature is the provision, in such af system fof, means -Wherebythe subscriberat the private exchange uponthe termination ofi a yconversation With a.` calledv main ex. change subscriber releases all the apparatus ata the private-exchange' involved vin setting upftlie. connection.

Other. features of the invention Will be disa-. closed aslthe description of the same .pro-

gressesfv For a morecomplete understanding of my in-ventionreferencei mayl be hadto vthe accompanying drawings -in which main exchange.,

' Eig/ lillustrates diagrammatically .acall-v ing Asubsoribensline, a linder switch', a start-f V ingcircuit Jand the groupvpbusy alarm;

Fig. 2 illustrates diagrammatically a connec-tor switchand a Vcalled subscribers line, and an outgoing trunk circuit to a two Wire automatic yexchange y Fig.` 3 illustrates fdiagrammatically the. ap paratusatth'e attendantsstation for comipleting fan incomingwcallj "from an automatic 6e Referringmore lparticularly to the drawP ings, Fig, Il discloses asubscribers station Af of ,the usual type `c0nr 1 ected by conductors l and-52 to the yprivate automaticexchange where, it terminates inline circuit L which; consistsof the li'ne rel ay L Rfand cut, cifrelayCO; The finder sWitchFSjcomprises a` motor ymagnet, MMj'which automatically opf crates When acallis initiatedjby the-`sub scriberat vsuhstationgA to step the Wipers.3,j 4,1 5 and `6 'overth'e v ba`nk contac,ts 7 ,8, 9 and 10 'to .se1ect the contactsofthe. calling f1ine. A bridging relay BG 'is provided and enerf gizes -Wh'entlie calling y1i ne f.is .seiz'ed by the sWitchFS. to shunt the motor magnet toE prevent further advancement 0f the kWip-V ers, ,4,-5 andfand'to connectthey calling line tothe connector switchCSj The sleeve relay SL[ .energiZes upon ,the actuation of "re-v layBGto extend ythe starting conductor 1 1 tok thcs next inderswit'ch FSof the group (not shown) L, A release ,magnet ARE which energizes torestore thenwipers 3,4,15and16 tonormalfis alsopprovidedL A supervisory relay SR is, provided `and operates Whenthje subscriberz actuates his'` dialing mechanism tor operate the COnneCtQrSWitClLCSL A lousy:l ing relay BR isprovided toi cause thevrelay bof the group busy alarm GBA- to operate,

The startingcircuit SG isprovided to connectthe-V group of finderI switches ofr kwhich FrS-is onev to ground fat 'whichever ofl the line relays. hasoperatedj A, pli'iralityLA of 'keys le, kf, k?, Ok3 and k* are provided' and Connect theiinder, switches of lthe group to a common conductor CC., Algroupvbusy alarmvG'BA is associated with the startingcircuit SC fand comprises sa, series of; busyingrelays bg bf, Il@ bt andfb., .a busy tone connecting relayb'e n u la,group .husy lamp GBLgand a groupbnsy l1 tone GBT which is connected to the calling subscribers line when all the finder switches of the group have been rendered busy. A ringing tone machine BTM is also provided. This machine is set into operation when a finder switch FS is selected to provide the ringing current for signaling the desired party and for supplying the ditlerent tones to the system. Y

The connector switch CS shown in Fig. 2 is of a construction substantially similar to that of tl e finder switch FS and comprises a shaft carrying wipers 13, 14, 15 and 16 which are adapted to be stepped into engagement with the contacts 17, 18, 19 and 20 through the medium of a motor magnet MM. A release magnet RE is` also provided which when actuated releases the switch wipers 13, 14, 15 and 1G and restores them to normal. The connector switch is of the rotary type and the tens contacts of the bank contacts 17, 18, 19 and 20 are left blank, that is, the tenth, twentieth, tbirtieth, etc. contacts are not connected to a subscribers line but are left blank or on open circuit. Assuming that a subscriber is calling a subscriber whose line is connected to the twenty-fifth set of contacts; the subscriber will operate his calling device to send ten impulses which will operate theconnector switch CS to cause the wipers to engage the tenth set of contacts in the bank which are blank. The subscriber again actuates hisdialing mechanism to send the second group of impulses which will step the wipers of the connector into engagement with the twentieth set of contacts of the bank which are also blank and the nal five impulses will step the wipers of the switch into engagement with the twenty-lifth setl of contacts which are the contacts ofl the wanted line. 1f the tenth and twentieth setsV of contacts had a subscribers line connected thereto which was connected in a conversational circuitk there would be interference with the connection when the wipersV engaged the tenth and twentieth set of contacts but by leaving the said contacts blank the wipers will not cause interference with an established connection in setting up another connection. A guard relay GU, a supervisory relay SR', a secret service relay SS,a ringing cut off relay RGO and a ringing trip relay RT are also provided. i

In the upper right hand corner of Fig. 2 is illustrated a called subscribers station B which is connected by conductors 21 and 22 to a line circuit similar in detail to line ciprcuit L as shown in Fig. 1. The apparatus necessary to extend the subscribers station to an automatic,main'exchange comprising a. line relay LR, a cut on? relay CO and a retardation coil RC is also shown. When Fig. 2 is placed to the right of Fig. 1 the two show the complete circuit arrangement.

Fig. 3 shows the apparatus at the attendants station of the private automatic exchange necessary to extend an incoming call from a main automatic exchange to a subscribers station or to complete an outgoing call for a subscriber. The apparatus dis closed consists of a line relay LB2 which is actuated by current from the main exchange over conductors c and c to operate the line lamp LL. A cut off relay CO2 is provided to disconnect the line relay LB2 from the conductors c and c. A holding key HK is adapted to connect a holding relay HR across the talking conductors Vto operate a hold and disconnect lamp HDL which may also be operated upon the energization of a disconnect relay DR. An operators set OS is provided and may be connected to the talking conductors through a listening key LK and a dial keyDK or to an information line com.- prising the conductors 140, 141 and 142 which are connected to a bank of contacts as shown in Fig. 2 by means of the information key 1K. A connecting key CK is also provided.

Having described in genera-l the circuit arrangement of the apparatus used in my invention I will next describe the operation of the same in establishing the different connections. Assuming that the subscriber A desires to converse with a subscriber B located at the same private automatic exchange.

The removal of the receiver at A closes the switchhook contacts at A which establishes an energizing circuit for the line relay LR of line circuit L; current flowing from battery, through the upper winding 23 of LR, normal closed contact 24 of relay CO, conductor 2, through the now closed switchhook contacts at the subscribers station A; conductor 1, normal closed contact 25 of GO and to ground through the lower winding 26 of relay LR. The line relay LR energizes and closes its alternate contacts 27, 28 and 29. The vclosure of contact 28 grounds the conductor 30 and causes the'motor magnet MM to operate to step the wipers 3, 4, 5 and 6 into engagement with the first set of contacts 7, 8, 9 and 10. The energizing circuit of motor magnet MM may be traced from battery, resistance r, motor magnet MM, normal closed contact 31, normal closed contact 32 of the ofi' normal contacts ON, conductor 33, closed contact 34 of sleeve relay SL, conductor 11, normal closed contact 35 of key of the startingl circuit SC, common starting conductor cc and conductor 30 to ground at alternate contact 28 of LR. The circuit of the motor magnet MM is opened upon the first step of the wipers 3, 4, 5 and 6 due to the opening of contact 32 of the off normal contacts ON which assume their alternate position upon the lirst movement of the wipers 3, 4, 5 and 6. A substitute circuit is established if the irst set of contacts 7, 8, 9 and l() are not the con tacts of the line of the calling subscriber A.

nsnagwof This eircuitis traced afromibattery, resistanceV 7"; motor magnet MM; closedfcontactil, altere nateifcon-taet E32-,1 conduct'orrf, normal closed contattiffllof-sfrelay SIR; conductorsv 38,-. to ground abnormal-'closed contact 39 inf/bridge ing) relay4 BG.: f The y motors magnet is.I thus; again-energized `I"toy step.' the wipers into. ens. gagementfwith rthefnentsetof oon'taetsi The cont act-SL31'. isunoved Stom itssalternateposition and thus: opens the fenergizingoircuit ofithef motorE magnet MM` wha'chi` irnmediatelyr-v ree leases zitsarmature 'andaagailry closes Contact 31 lto'establish'- another fenergizingcircuit fr thee motor i magnetfxMM to@ again'v4 ste nentfsetfof. conlmcts.-`v The alternate-opening andv closing ofthef contactf; Bil; causes-I the wipers tof. stepped over theacontacts 'f 7, ,-8; 9.?and` l() in! searclizof #the cmataetsfof'theacalle `ingrlinie.' Ai condenserrvis'Abridged across alternateContacty 27; ofi-.linerrelayzLRp The instant wiper Ltxlengages grounded :contactrS orti the callingline the circuit/just` traced closes a 1 low; resistance i path. throughs the lower;Windingstl3 of the; bridgingrelay BG to shunt the motor. Ymagnet*MM and prevent th'e. fnrtller4 `operatiofni offthe` samee. Upon energizing BG-f openszthe.v circnit of; motor inagnetMM atits contactf39v and establishes an'=.energizing`ci1c1iit for the' sleeve. relay? Sli and entf oil-1: relay kG@ f whichv rmay' fbe traced from battery 'throughthei upper Winding .45

ofs SL, conclctorzl-, .alternate contact- 47 of BG, conductor.'Y 481;..Wipers 3,- ,contact- 7 .cons duetori49nto ground' through cutoff:1 relay CO which energizes; and r`op ens its. contactsff and 251m deenergize: LRwhiclr i removes:v ground from. Contact1 8" anclconcluctor 30; Thearea merca-lief; ground from Contact .f8 allowsf'the wipers; of-another .finderrswitcha.:toipassrover the line of snbseriberLAlshonld another finder switch?r ofi the l group be operated While A .is connected tolinrler sWitchIt-:S Tliefheavily marked' i talking f conductors'. 2 are closed atriali ternate` cmitacts t50 and L 51'. The closing 'ot' contactQ of relaySL closes-a locking circuit forSL tracedfromfbattery through theflower Winding-fofSl, alternate contactLQ of SL and-to Ygroand'atalternate y'contfwtf54 of olf normal-contacts @NsE This circuitlmailntains tlesleevetrelayfSE in it'slenergized condition; Upornthet closureL ofifalternate# contactsQ 50 and 5:1 of'iBG an:energizing-tcrcuitiis; established .rom-the superysory/relay JSR- which may.' be.L traced fromybatteryf throughthe lowerzwinding of'zrelay: SR, alternate Contact 51` off BG,` Wiperf .and acontactrlO Sover; the.

and baclrzthrol'xgh contact 9 andziwiperr, alf` ternateeontact 50i andto. ground through. .theupperzrs'finelingy 'of' SR1... Relayy Slt-energizes and closes its yalternate Contact? 55. whichy energizeshusying relay BR `over.'atcireuit traced from.batteryithroughllthe Winding of subscriberfs line. through.. the. suhstationyl/V BRtconductor-. .to ground iatalternatecon-i f tact 55 orSR; The openingjoffcontact 44 of `s SL interrupted the Aoriginal energizing circuitrobridging relay BG but-apsubstitute circuit is closed through alternate make be@ fore break contact-58 ofBRand thefbridging relayi BGis `inain'tainedenergized by' current flowing' froinf. hatteryr'through' fresistanees r; conductor.40,.lower Winding.` 4:1: of 'BlG,c0n dnctorfr, alternate.-I contact' 58= to ground through'iupperawindingfffofBG;

Thel closing of contactrrlOfofBR estab.` lishes: an operating 1 circuiti for the' ringing tone machinefR'TM which thereupon' Voperates te.- supplyv ringing" current, .the group." busy7 tone,-y .the regular husyrtone andthe dial tone.A The circuitf forA R'IMi may be traced from groundjat normal4 con-tact 107 of-"RCO, conf duetorflO'; alternatecontactplO: ofa BR to batteryv at :the Iringing tone machine. RTM

Then sleeve relayfSL Aoperates it'closes its alternate contactffl which: ext-ends the: com-- mon4 starting conductor ce to fthe next finder The I"removal of'the receiver latfthe. substation Will operate the `line relay of the connected `line circuitr Which willfcause ground tobe the==fifth switchis in=usethe1connectionwill be extendedover conductor 62H0 the second switch and ili'itisbusy thelconneetionwill 'be extended .to #fhe fourth switch overi' conductor Gil. If' all 'thefswitcli'es ,are busy? the subscriber willv receive-a group busy: tone: as Will he hereinafter described.

lf lit f is `desired' to remove any of the finder switches Aoli' the group from operation'the key of?" the starting:v circuit associated With the {incl-er switclito .berremoved may lbemoved to its alternate position. F 'or' instance if"V the finder switch'FS isV the one to be cut out of the group the key c will be operated and contarts 35 and 63 will assume their alternate positions. The common starting conductor cc will in such case be connected directly to conductor 61 through alternate contact 35 of key 7c and the ground connected to any of the conductors 30, should a subscriber call, will be connected immediately to the next switch of the group and not to switch FS over conductor 11. The closure of contact 63 grounds conductor 62 and causes the operation of busying relay b of the group busy alarm GBA by current flowing from battery through the winding of relay over conductor 62 to ground at alternate Contact 63 of key la. Y

Upon the operation of busying relay BR of the finder switch FS an energizing circuit is established for the relay Zi traced from battery through relay b and conductor 64 to ground at alternate contact 65 of relay BR. The relay b operates and closes contact 66 which is grounded. The relays b', b2, b3 and b4 are each associated with a finder switch of the group and with the correspond ing keys 7c, k', k2, 7c3 and 704 of the starting circuit SC and are electrically connected to the saine by conductors 64, 64', etc. and conductors 62,62', e c. Vlienever a finder switch is connected to a subscribers station the busying relay BR of the finder switch will close an energizing circuit for the relay b', etc. associated with it. Likewise the operation of any one of the keys la, c, etc. of the starting circuit will operate the associated relay Z), etc. to cause it to close its contacts 66, 66', etc. lf all the finder switches are busy or are out of use and the associated key 7c, la', etc. is operated an energizing circuit for the group busy tone connecting relay bc will be closed. This circuit may be traced from battery through the relay Zic, alternate contacts 664, 663, 662, 66' and 66 of rela-ys b4, Z13, b2, 7) and b to ground. The relay bc will operate and close its contacts 67, 68 and 69. The closure Y of contact 67 establishes an energizing circuit for the ringing tone machine RTM traced from ground, alternate contact 67 of be, to battery and ground at the ringing tone machine RTM. The closure of contact 69 operates the group busy lamp GBL and the closure of contact 68 connects a group busy tone device GBT to the subscribers line to give a distinctive tone to the subscriber to inu form the subscriber that all the finder switches are 1busy. This tone may be traced from the group busy tone device GBT, through alternate contact 68, conductor 69, alternate contact 29 of the relay LR, asso ciated with the calling subscriber, conductor 1 to the receiver at the subscribers substation.

It will be remembered that the relay BG had energized to connect the subscrbers set at A to the connecting switch GS. As soon as the rela BG operates t0 connect the finder switch F to the connector switch CS the subscriber will receive a dialing tone which informs the subscriber that the dialing may be started. This tone may be traced from the dial tone mechanism DT, normal contact of off normal springs ON', conductor 76, normal contact 77 of RGO, conductor 78 to the heavily marked talking conductor and thence to substation A over the line. The subscriber at A operates the calling device CD which interrupts the energizing circuit of supervisory relay SR causing it to restore its contacts to normal each time the energizing circuit therefor is opened. `As soon as contact 55 of SR is restored to normal an energizing circuit is established for the motor magnet MM and the guard relay GU traced from battery through the lower winding of relay GU and from battery through the winding of the motor magnet MM', normal contact 7 0 of the busy tone relay BTR, normal contact 71 of secret service relay SS, normal contact 72 of ringing cut off relay RGO, conductor 73, alternate contact 74 of BR, normal contact 55 of SR. The motor magnet MM energizes over this circuit each time the relay `SR restores and steps the wipers 13, 14, 15 and 16 into engagement with the next set of contacts. The guard relay GU energizes and opens its Contact 79 to prevent the secret service relay SS from operating as the wipers 13, 14, 15 and 16 pass over the contacts associated with unwanted substations. The guard relay GU is slow to release and remains energized during the interruptions caused by thev opening and closing of the contact 55. Relay BR is of the slow to release type and the rapid flickering of contact 55 has no effect upon the relay BR which remains energized during the dialing by the subscriber. After the dialing has been completed and the contacts of the wanted line have been engaged by the wipers of the connector switch CS and guard relay GU returns to normal as its energizing circuit has been opened at the contact 55.

If the desired line is busy the closure of contact 79 of GU establishes an energizing circuit for the busy tone relay BTR traced from battery through the winding of BTB, normal contact 80 of relay SS, conductor 81, normal contact 79 of GU, wiper 13, contact 17 to ground through the cut off relay GO of the line vcircuit to which subscriber B is connected. Relay BTR operates and connects a busy tone to the calling subscribers line to indicate that the called line is busy. This tone may be traced from the busy tone device BT, alternate contact 82, conductor 83 to the heavily marked conductor and thence over the line to the subscriber at A. The opening of contact 70 of BTR opens the energizing circuit of motor magnet MM and prevents the subscriber from again opcircuit. ofi-BG at contact-58. .and BG restores-` closingitscontact 39 whichenergizesthe re- .f lease :magnet :Current flowing from 15 f. battery, through RE, alternate contactI of /.SL, -.conductor 881normalvv Contact -39 .to ground. 'Release :magnet 4RE a restores -the -wipers 3, 4, "tandI 6 land offy normal springs .)l\lto.n normal. -Thesopening .off of. normal rg0 contact 54 opens the locking circuit of SL'and rit-restores to normaL. opening jits .contact 34 ..-vvhich-'fagain.puts thetfinderjswitchinconditionto; beseized .by another.subscriber..4 ,The .opening of; 'contact V65. of IBR-:opens the ener-y vU25 .V gizin-g" l circuit off relay I b-.of a the ggroupnbusy .alarm GBAJand it opens its contact. JThe :restoring to V:normal of contact .86L 0f.- BG-es- .itablisheswani energizing circuit, for they .ring. ting .cut of relayfRGOof theeonneetorswitch AF80 aGS AWhich ,may lbe itraced y#from) battery..

.. through :the lower. .windino' f of ,relay RGO,

i alternate. contact 1.87 lof o y','normal springs QON Ywhich assumed their f iof .f normal J,posi- A.ation t uponi the first; movementl oflthe wipers F35 .r1-3, 14,.i1Y5a-and [16, .conductor 88 to.groundat :anormal :contacte 86 loil-BGLV -This establishes :flanfenergizing I circuit .for the.v release.' magnet -RE"1 traced: from battery, through* the' windingREQnormal contact 84 SS, conductor iV g Y i ringingiripr. relay-RT. traced over-"theringm5 ving-current pathfbut through .theclosed fswitchhook contactsatB RelayfRT enel'- ,gizesandcloses its contact 100g-Which. estab-y 40 "85, Ianormal 1 contact JM, `conductor 73, to ground-fat alternate contacts (1f-RGO.. :The release magnet RE. operatesand restoresthe Wipers.f13, 1114, :lsand land the-'off normal @contacts ONf tofnormal. y .Theopening-oftdt f *15 `normalsprirugf opens athezenergizing cir.-

cuit of RGO Whichldeenergizes-and topensA the rcircuit 'of RE. .The energizing circuit ofirelay BTRis interrupted When-'Wiper v13 treturns; to: normal soallf the apparatus used.y is

550 :new etrnormal. Y {Assumenow thaty thefcalled linewas idle. .The restoring to normalot contact-7 9 'of GU cuponi the. cessation: of dialing 'establishes an @energizingcircuit'for.thesecretservicerelay *55 .TSS which 'may .be traced .from `.battery wthroughthe Windingzofrelay SS, highlre y Y u L .contactsf94 and 95.0ver theheaVily marked conductors. `An energizing circuitfor thesuperyisory .relayv SR is .also vestablished by fr the. closing. of alternate. contacts'94 and9`5 of.125 .-RCfO. This `'circuit may.. be; traced. from' battery. through .the lower .Winding of SR, Vcon- .si'stanee Winding 89, :conductor 81, normal {contact (-9,.Wiperf13,= and contactl? toground @through thewinding otthecut oit-relay assoy`soon .asf relay SS. operates .a lockingcircuitis Y established, forthe relay .SS through itsalternate 'contact :substitute ..circuitv ...-shuntsg-outthe high resistancewinding89and n i l y l :tact QO oyerthe subscrlbershne andA c1osedl, j

.' T5 c.allows f cut of the called sub.-

f-scribers line 5to: operate .to cut y.ol .therline relay `l from?.theealled subscribersline. :The sbunting of .the high resistance Winding.' 89

substati on' B `.because the. relayf. SS-in the secone! .connector `switch. which has 'itsv Wipers enegagingk muitiple contacts of. the calledwline willtail to` operate due to thehigh resistance Winding 89 of 'the second connectorgbeingin` 75 the errergizingfcircuit. l The SS t. of-.the i' `second connector-.fallingto .operate the; relay Dirt off. the, second switch will operate. and

the V,processfwillzbeasi before described. Thev energizing of SSalso .closes contact-S90, 91 80 and 92 `which immediately, connect lcurrent Vto the called subscribersfline. .The

.v circuit: forthe ringing current may` be traced `from/.assourceof ,interrupted generator currentlGEN,conduetor /93,.-.normal. 'contact 94 $5 of ringinglcut off relayRCO, alternatecon.- tact. v92-.o:t.SS, Wiper 1.6,. contactQQ,overy the fsubscribes line. through thezbllA .atthe s substationtB, contact 19,'wiperl5, closed con- Ytact 90 of SS,- normalfcontact 9.5. ofRCO,rco11-: 90 1 `ductorJ `96 and` through. the Windingof ring.-

ingtrip relay.RT baclctothe .sourcelof generator. current. vArevertiwa ringing system is provided to f y.inform-the. `calling subscriber Afthat`1 the signaling; ofMBH has commenced. 95 This circuit ymay be traced from alternate contactsy 90.7.anl :91. OSS, conductor9?, con- 'denserY 948, retard coil-.99.. andover` the. .heavily 1 markedn conductors. -to the` receiver ,at station A. yThe. ringing current'` isapplie'd' .intermit- :I4 .100

tently, untiLthecalled subscriberB answers or tl1e:.calling subscriber y abandons the` call. Upon the removal 4of the receiverat station .B .an.energiziug .circuit .is established Jfor .the

lishes an energizingcircuitffor ringing .cut

. ffrelayRCOaWhich may be trace'dfromv batl 110 .tery .through -the upper Winding ofRCOfA conductor101,:alternatecontact lOOof-.RTto

. ground. t Relay, RCC closes locking. .circuit Efor.. itselflwhi'ch maybe .traced .from battery n through the*l lowerwinding, O'RCO, alternate 115 yductor'103,ralte`rnate contact".94',.of'RUG, al-

ternatefcontact 92v ofV SS, Wiper .16, conswitchhook contacts,back through contact 19 subscriber A through the windings of the su'-v pervisory relay SR and to the talking circuit of the subscriber B through the supervisory relay SR.

Upon termination of the conversation the i subscribers at A and B replace their receivers upon their respective switchhooks. The replacement of the receiver at A opens the energizing circuit of SR which restores to normal opening its alternate contact which breaks the energizing circuit of relay BR which restores its contacts to normal. This i last restoration opens the energizing circuit for relay b of the group busy alarm GBA which restores its contact 66 to normal. The restoration of contact 58 to normal opens the locking circuit of bridging relay BG which vrestores thereby opening the talking circuit at contacts 50 and 51Y and establishing an energizing circuit for the release magnet RE as previously traced. The release magnet RE operates and restores the wipers 3, 4, 5 and 6 and oil normal contacts ON to normal. The

locking circuit of SL is broken at 54 of ON but a substitute circuit is closed at normal i Contact 74 of BR. This circuit may be traced from battery, through the lower winding of SL, conductor 150, alternate contact 84 of SR, conductor 85, normal contact 74 of BR, conductor 73 to ground at alternate contact 72 of RGO. The sleeve relay SL and release magnet RE remain energized and under the control of the subscriber B through the medium of the supervisory relay SR.

The replacing of the receiver at B breaks the circuit of supervisory relay SR which restores its contact 84 to open the circuit of I relay SL which restores to normal and opens the circuit of release magnet RE which restores. All the .apparatus of the finder switch FS is now at normal and the opening of alternate contact 34 places the switch FS in position to seize another calling line and the closing of normal contact 84 of SR establishes a circuit for the release magnet RE which circuit may be traced from battery through the winding of RE', normal contact 84 of SR, conductor 85, normal contact 74l of BR, which restored to normal as above described, conductor 7 3, to ground4 at alternate contact 72 of ROO. It will be noted that the release magnet of the conductorswitch CS cannot operate until the subscriber A has replacedrhis receiver to restore the relay BR. Release magnetv RE restores the wipers 13, 14, 15 and 16 andol normal contacts 75 and 87 to normal. Therestoration of contact 75 of ON breaks the locking circuit of ROO which restores its contacts thereby breaking the energizing circuit of release magnet RE at contact 72 which restores. The circuit for relay SS is broken at wiper 13 which the release magnet RE restores and all the apparatus of the connector switch is at normal. The release of the connector switch OS is entirely under the control of the called party and cannot take place until the called party hangs up. 'This prevents the operation of another finder switch to locate the calling line should the called party fail tio replace his receiver before the calling party oes.

s Certain sets of the contacts 17, 18, 19 and 20 are connected to trunk lines which interconnect the private automatic exchange and the selected trunk line, but the busy tone relay BTR Vwill energize over a circuit traced to ground through line relay LR ot the trunk circuit. The operation of BTR opens the energizing circuit for the motor magnet MM at contact and connects the busy tone signal BT to the calling subscribers line at contact 82 as beforedescribed. Upon the replacement of the receiver at station A the apparatus is restored to normal in the same manner as described in the connection be-l tween stations A `and B.

If the trunk line selected is idle the secret service relay SS and line relay LR will energize. The energizing circuit may be traced from battery, through relay SS, conductor 81, normal contact 79, wiper 13, contact 17 to ground through relay LR. Relay LR closes a circuit at its alternate contact 108 for the trunk connecting relay TC which circuit may be traced from battery, relay TO, alternate contact 1 08, contact 18, wiper 14, conductor 60, alternate contact 56 of SR to ground. Relay TO operates and'closes its contacts 109, 110 and 111 to connect the subscriber at A to the trunk conductors c2 and c3 which lead to an automatic main exchange (not shown) and terminate in a line circuit similar to L shown in Fig. 1. The closure of contact 111 of TO connects the retard coil RO across the conductors 02 and c3 to provide an energizing circuit `for the line relay at ,the main exchange which operates and starts a finder switch P- erating to select the calling trunk line` The subscriber A operates the calling device GD whichV intermittently interrupts the energizing ycircuit of supervisory relay SR. The

opening and closing of contact of SR has no efect as the circuit of the motor magnet MM is open atcontact 710i relay SS but the flickering of contact 56 of SR breaks the circuit of TC and causes the trunk connecting relay TC to deenergize and energize each time the contact 56 is opened and closed ,Y thereby cutting the retard coil RC into and out of the circuit at its contact 111 which interrupts the circuit of apparatus situated at the mainexchange'to operate mechanism to select the desired party. As soon as the trunk line is selected and the relay TC has operated the retard coil RC' closes a circuit for the ringingtrip relay RT which'closes its -contact to cause the operation of ringing cut off relay RGO which disconnects the ringing current from the trunk `line by opening normal contacts 94 and 95. The supervisory relay SR is also Operated. by current flowing scribed. The restoration of alternate contact 56 of SR opens the holding circ-uit of relayy TC which restores to normal opening its contacts 1'09, 110-and 111.v The lopening of the 'contacts 109 and 110 yof the relay TC causes the deenergization of the relay -SR which re'- stores its contact 84 to cause the operation or' the release magnet RE which restores the `connector switch CS to normal in the same manner as described in the connection between the subscribers A and B. Both the 'finder switch FS and the connector switch CS vare under the ycontrol of the subscriber at the k,private automatic exchange when a trunk line is connected in circuit, that is the finder switch FS and the connector switch CS will not restore to normal until the subscriber at the private exchan e hangs up in which case theyy restore even t ough the main exchange 'subscriber has not replaced his receiver.

Incoming trunk calls can 'only be completed through the assistance of the attendant at the private automatic exchange. Assume thata subscriber at a main exchange desires to converse with a subscriber at the private automatic exchange and that the trunk conductors c and c have been selected as the 'trunk .line to be used. Ringing current is ltransmitted from the main `exchange 'over conductor-c, normal contact 1,12 'of cnt off relay (302, conductor 113, condenser 114,

line relay LB?, normal-contact '1150i C02, conductor c to the main exchange. The line relay LR2 operatesand closes `its contact .116,

which remains in its alternate position after ,Y

the line relay LRZ has deenergized, and closes a :circuit for the line ylamp LL; said circuit being traced from battery through the 'la-mp LL to ground at alternate contact 116 of LR?. The attendant notices the lamp LL glowing and ldepr'esses the listening key LK to connect the operators set -OS .to the trunk conductors c 1and c.' An energizing circuit for cut of relay CO2 is closed and the rrelay operates and closes its alternate contacts 112 and 115 which extend the trunk conductors c and c to the attendant .and also cut off the line relay LR2 from the trunk conductors c and c". The attraction of armature 112 restores the contact' 116 of LR2 to norma-l to elface thefline lamp LL. The relay CO2 is energized by curren4 flowing from battery through the winding of CO2, conductor 117, normal Contact 118 of LRZ, conductor11'9, normal contact 120 of dial key DK, to ground at alternate Contact 121 of the depressed listening key LK. The operator inquires ,thel wants of thel calling party and ascertains that the subscriber- B is wanted. The oper-V atorsset 0S is connected'in a conversational circuit with the main exchange subscriber yai over trunk conductor c, alternate `contact y 112 of CO2, conductor c,`normal contact 123 of dial key DK, alternate contact 124 of LK,

the operators setOS, alternate contact 125 of U LK, normal contact 126 of DK, conductor c7, alternate contact 115 of CO2 and conductor e. Itis over this circuit that the operator learns lthe desires of the calling party; battery for the talking circuit being supplied at the main exchange. The operatordepresses the holding `key HK which establishes an energizing circuit for the holding relay HR which is operated bycurrent flowing Jfrom the mainexchange, conductor c, Aalternate contact 112, conductor c6, closed contact 127, relay HR, closed Contact 128, conductor c?, alternate contact 115, conductor c to the main exchange. The Contact 129 of HR is closed and connects ground `to the hold .and disconnect lamp HDL to illuminate vthe lamp HDL which informs the voperator that the trunk line c--c is beingheld. The key HK is left in its-depressed condition andtheina trunk line is held through the contacts 12.7

and 128 and relay HR and contact 130 places an tadditional ground on conductor 119 to hold relay CO2 energized. The conductors c4 and c5 are connected to a line circuit similar to Lof Fig. 1 and associated with a finder switchFS and connector switch CS. The

operator next depresses the dialing key DK which opens its ycontacts 123 and 126 to disvconnectthe operator'ls setOS from the trunk erators set VOS to the line circuit at the private `exchange over conductors 04 and 05 which causes the energization of a line relay LR and the operation of a finder switch FS which finds the contacts 9 and 10 associated with the conductors c* and c5. The attendant operates the calling device CD and causes the connector switch CS lto find the line of the called subscriber B Vin the same manner as explained in the connection between A and B. As soon as the subscriber B answe the operator throws the connecting key CK and releases the dialing key DK and listening key LK which disconnect the op erators set OS from the connection. The holding key HK is also released and the opening of contacts 127 and 128 interrupts the circuit of HR which restores to normal and effaces the lamp HDL by opening contact 129. The .cut olig relay CO2 is maintained energized over the circuit before described ground being furnished at alternate contact 133 of CK. The supervisory relay SR of the finder switch FS is maintained energized over apparatus at the main exchange and consequently upon the termination of the conversation and the replacement of the receivers the finder switch FS and connector switch CS will be restored as before described. However, the deenergization of relay7 SR and subsequent restoration of CS closes normal contact 134 of SR which establishes an energizing circuit for the disconneet relay DR of Fig. 3. This circuit may be traced from battery, through relay DR, conductor 135 which is connected to a contact 8 of the line circuit associated with the conductors c4 and c, wiper 4L, alternate contact all of SL, conductor .136, resistance r, normal contact 134, conductor 137 to ground at normal contact 102 of RGO which restored to normal upon the movement of off normal contacts ON. The relay DR operates and closes its alternate contact 13S which closes a circuit to ground for the hold and disconnect lamp HDL. The attendant noticing the lamp HDL glowing realizes that the conversation has terminated and accordingly restores the connecting key CK which opens the crc-uit for CO2 at contact'133 which deenergizes and disconnects the conductors c and c from the conductors c6 and c7.

Should a subscriber the PAX desire to call a subscriber' at a main exchange, he may have the attendant complete the call. A subscriber such as A will dial the number given the information line which is the one leading to the attendants station. i lVhen the wipers 13, 14;, 15 and 16 engage the contacts associated with the information line a circuit for the information lamp IL is established. This circuit may be traced from battery, through the lamp 1L, normal contact 139 of informa tion key IK, conductor 140 which leads to ground atalternate Contact 143 of the cut off relay associated with the line circuit of the information line. The contact 143 of cut off relay CO is used only in the line circuit of the information line and contacts 18 are used only in connection with trunk lines and are not used in connection with subscribers lines or the information line. rlhe glowing of the information lamp IL apprises the attendant that a subscriber desires attention and the attendant operates the information key IK. The closing of contacts 144 and 145 of 1K connect the operators set S in a talking circuit with the subscriber A, through the switches FS and CS, contacts 19and 2O and conductors 1111 and 14.2. The attendant inquires the wants of the calling subscriber and is given the number of the desired party located at the main exchange whereupon the operator instructs the calling subscriber to replace his receiver and the attendant restores the information key IK and the finder vswitch FS and connector switch CS restore duev to the Opeliing of the energizing circuits of supervisory reiays SR and SR as before described. The attendant throws the listening key LK which connects the set OS across the conductors c and c through the alternate contacts 112 and 115 of CO2 which operates upon the closure of contact 121 of LK. The operator next operates the dialing mechanism CD which affects apparatus at the main exchange to cause the connection to the called subscriber. Upon the answering of the called subscriber the attendant operates the holding key HK to hold the trunk connections and proceeds to call the originating or calling party in the same manner as described in connection with an incoming trunk call. The release of the apparatus also is accomplished in the same manner.

'Vhile I have described a preferred embodiment of my invention l do not wish to limit myself to the same as modifications and alterati ns may readily suggest themselves to one skilled in the art, I therefore claim everything within the spirit and scope of the appended claims.

Having described my invention, what l claim as new and desire to secure by United States Letters Patent is:

1. In an autoi'natic telephone system of the character described, a plurality of telephone lines terminating at a private automatic exchange, a group of finder switches for locating a calling line, a group of connector switches associated with'said finder switches, a calling device, said connector switch operable upon the actuation of said calling` device to connect said calling line to a called line, a common starting conductor for said iinder switches, means for extending said common conductor` to the next iinder switch -of the group, a busy group alarm comprising a plurality of busy relays each associated with a finder switch, means in, said {inder switches for operating-the Aassociated busy relay in said busy group alarm whenk said finder switch locates a-callin-g line. f

2.. In an automatic telephone system a plurality of telephone lines terminating at a privateautomatic exchange, `a group of iinder switches for locati-ng a calling line, a group of connector switches associated with said linder switches for extending said calling line to a called line, a common starting conductor for said group of finder switches, means in each of said inder switches voperable upon the connection of a finder switch to a calling line for ext-,ending said common conductor to the next finder switch of the group and switching means for removing any one'o'f said finder switches from said group.

3. In an automatic telephone system a plurality of telephone lines terminating at va,

private automatic exchange, a group of finder switches for locating a calling line, a group of connector switches for extending said calling line to a called line, a common starting conductor for said finder switches, a busy group alarm. comprising a group of busy re-y lays each associated with a finder switch, means in said finder switches operable upon the location of a calling line by said finder switch for extending said common conducf tor to the next iinder switch and for operating the associated busy relay in the said busyr group alarm. v 4. In an automatic telephone system a plurality of telephone lines terminating at a private automatic exchange, a group of connector switches for extendlng a calling line to a called line, a common starting conductor for said finder switches, a busy group alarm comprising a busy relay each associated with one of said finder switches, relay means in each of said finder switches operable upon the connection of said finder switch and said calling line to extend said starting conductor to the next iinder switch of the group and to operate the associated busy group alarm,

and switching means for removing one ofr said finder switches from the group and rfor extending said starting conductor to the next finder switch and for operating the busy` relay associated with the finder switch removed from the group.

5. In an automatic telephone system, a plurality ot' telephone lines termina-ting at a f private automatic exchange, a group of tinder switches :tor seizing lines as calling lines, a group ot connect-0r switches for connecting said calling line to a called line, a ringing tone machine supplying a plurality of tones and ringing current to said system, means operable upon the seizure of a calling line by a finder switch to start said ringing tone machine, and relay means for stopping said ringing tone machine.

y6. In a telephone system of the character switch for. joining said source to the calli-ngv line when the said connector switch is in ycircuit with said calling line.

7. In an automatic .telephone system a plurality of telephone linesterminating at a private automatic exchange, a group of finder switches for seizing lines as calling lines, a groupof connector switches for connecting said calling line to an idle called line, a common starting conductor, a `group busy alarm comprising a group of busy relays each associatedy with a inder switch', relay means in said finder switch operable upon the con'- nection of said finder switch and said calling line to extend said starting conductor to an idle Iinder switch and to operate the busy relay associated with the said .finder switch,

a group busy tone device, a. busy connecting relay in said group busy alarm operable when v all the finder switches are busy to connect said groupbusy tone device to a calling line.

y8. Inan automatic telephone system a plurality of telephone lines lterminating at a private automatic exchange, a group of finder switches for seizing calling lines, a

group'of connector switches for selecting idle called lines, a calling device for said calling line, a dial tone device, a busy tone device, a

separate group busy tone device andv relay. means forconnectmg said tone `devices toV said calling line.

k9. A ytelephone system comprising telekphone lines terminating at an auxiliary ex-y change, finder switches and kconnector switches :connected in pairs to form a connecting circuit for interconnecting saidrlines as calling and called lines,-an automatic main exchange, trunk linesk extending from said auxiliary exchange Ito said main exchange, a callingfdevice adapted to operate said Aconnector switch to lselect atrunk line, means in said trunk line responsiveY to said calling device for operating mechanism at said automatic main exchange to complete a callto a subscriber at said automatic main exchange, a source of dialing .tone and means forjoining said source to a calling line when one of said connector switches becomes operatively connected thereto.

10. A telephone system comprising local subscribers lines terminating at an auxiliary exchange, an yautomatic main exchange, trunk lines extending between lsaid main and auxiliary exchanges, a inder switch adapted to seize a localr subscribers line as-a callngf line, acallmg device ingsaid calling line, a.

Asaid attendants station and said main exchange and means at said attendants station for connecting a local calling line to a called subscribers line at said main exchange.

11. A telephone system comprising local subscribers lines terminating at an auxiliary exchange, an automatic main exchange, trunk lines extending between said exchanges, a. finder switch for seizing a local line as a calling line, a connector switch asso ciated with said linder switch, a calling device in said calling line, said connector switch responsive to said calling device to select a called local line ora called trunk line, said finder switch `and said connector switch forming a connecting circuit for interconnecting said lines, means in said trunk line responsive to said calling device adapted to operate mechanism at said main automatic exchange to complete a call to a subscriber at said main exchange, and release means under the control of the said local subscriber for restoring said finder switch and said connector switch, a source oit dialing tone and means for oining said source to a calling line when one of said connector switches becomes operatively connected thereto.

l2. A telephone system comprising local lines terminating at an auxiliary exchange, an attendants station, a main automatic ex- A change, incoming trunk lines extending be-V tween said inain exchange and said attendants station, signaling means at said att-endant`s station for apprising the attendant of an incoming trunk call from said main exchange, a finder switch and a connector switch for interconnecting said attendants station and a local line, said finder switch and connector switch responsive to means at said attendants station to select a local called line, means at said attendants station for extending said incoming call to a local subscribers line, and a disconnect signal at said attendants station under the control of the local subscriber for signalling for a disconnection.

13. A telephone system comprising local lines terininatingat an auxiliary exchange, an attendants station, a rnain automatic exchange, incoming trunk lines extending between said main exchange and said attendants station, signaling means at said attendants station for apprising the attendant of an incoming trunk` callfrom said main exchange, a finder switchA and a connector switch for interconnecting said attendants vthe local subscriber for signalling for a disconnection and means under the control of said local subscriber for restoring said finder and connector switches.

Signed by me at Chicago, in the county of Cook and State of Illinois, this 22nd day of October, 1929.

MICHAEL B. STAZAK. 

